Comparing the Importance of Hemodynamic Obstruction with Diastolic Dysfunction in Patients with Hypertrophic Obstructive Cardiomyopathy

Abstract

Objective: Myomectomy is the cornerstone of therapy for hypertrophic obstructive cardiomyopathy (HOCM) in the presence of a high gradient. The importance of mechanical gradient across the left ventricle outflow track (LVOT) vs left ventricular diastolic dysfunction (LVDD) is debatable. Methods: We retrospectively analyzed data on 14 patients with HOCM who underwent myomectomy from 2007 to 2011 at our institution. All patients in this study were symptomatic. The purpose of this study was to assess the significance of immediate reduction of the gradient across the LVOT as well as improved LVDD and its correlation with hemodynamics. Results: A total of 14 patients with a mean age of 52.5 ± 19.0 years (male-female ratio of 5/8) were evaluated. The preoperative LVOT peak gradient was 76.9 ± 63.4 mmHg, the left atrial (LA) diameter was 41.9 ± 6.1 mm, and the septal thickness was 15.4 ± 3.2 mm. The relevant preoperative risk factors included DM (23.0%; n = 3), angina pectoris (15.4%; n = 2), cerebrovascular disease (CVD) (30.8%; n = 4), stroke (15.4%; n = 2), arrhythmias (30.8%; n = 4), and COPD (15.4%; n = 2). The concurrent procedures included mitral valve repair/ replacement (MVR) (30.8%; n = 4), aortic valve replacement (AVR) (23.0%; n = 3), coronary artery bypass grafting (CABG) (15.4%; n = 2), and modified MAZE procedure/ablation (15.4%; n = 2). The perioperative mortality was 7.7% (n = 1), and the long-term survival was 85.6% at a median follow up of 30 months. The postoperative LVOT gradient improved to 32.3 ± 24.4 mmHg and the septal thickness to 12.5 ± 3.8 mm. These differences were not statistically significant, likely due to small sample size. The postoperative complications included iatrogenic small VSD in one patient (who had myomectomy for a third time), atrial fibrillation (n = 4), cardiac arrest (7.7%; n = 1), neurologic adverse event (7.7%; n = 1), and new onset renal failure (7.7%; n = 1). We did not observe any new onset AV block. The length of stay (LOS) in the surgical critical care unit was 95.5 ± 112.7 hours. The overall hospital LOS was 15 ± 11.5 days. Conclusion: The septal myomectomy results showed an immediate reduction of the LVOT gradient, which translates into clinical and echocardiographic improvement.